This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A062824 #15 Mar 10 2024 07:52:35 %S A062824 0,0,0,0,5,0,7,0,0,9,8,0,0,10,13,0,15,0,41,0,14,19,12,0,21,16,0,53,0, %T A062824 25,0,20,0,16,22,31,0,0,33,18,77,0,26,73,0,0,39,18,89,0,43,0,22,45,32, %U A062824 0,20,34,49,24,0,0,113,0,86,55,0,0,105,40,0,125,28,61,24,63,44,0,46,121,0,26,69,0,149,0,50,73,24,34,75,0 %N A062824 a(n) = Ch(A005117(n)) where Ch(n) is Chowla's function and A005117(n) are the squarefree numbers. %H A062824 Amiram Eldar, <a href="/A062824/b062824.txt">Table of n, a(n) for n = 1..10000</a> %F A062824 a(n) = A048050(A005117(n)). - _Amiram Eldar_, Mar 10 2024 %t A062824 chowla[n_] := DivisorSigma[1, n] - n - 1; chowla[1] = 0; chowla /@ Select[Range[150], SquareFreeQ] (* _Amiram Eldar_, Mar 10 2024 *) %o A062824 (PARI) j=[0]; for(n = 2, 150, if(issquarefree(n), j = concat(j, sigma(n)-n-1))); j %Y A062824 Cf. A005117, A048050. %K A062824 easy,nonn %O A062824 1,5 %A A062824 _Jason Earls_, Jul 20 2001 %E A062824 a(1) corrected by _Amiram Eldar_, Mar 10 2024